Disposable personal care products, such as pantiliners, diapers, tampons, etc., are a great convenience. Such products provide the benefit of one time, sanitary use and are convenient because they are quick and easy to use. However, disposal of such products is a concern due to limited landfill space. Incineration of such products is not desirable because of increasing concerns about air quality and the costs and difficulty associated with separating such products from other non-incineratable articles. Consequently, there is a need for disposable products that can be quickly and conveniently disposed of without disposal in a landfill or incineration.
It has been proposed to dispose of such products in municipal and private sewage systems. Ideally, such products would be flushable and degradable in conventional sewage systems. Products suited for disposal in sewage systems and that can be flushed down conventional toilets are termed “flushable”. Disposal by flushing provides the additional benefit of providing a simple, convenient and sanitary means of disposal. Personal care products must have sufficient strength under the environmental conditions in which they will be used and be able to withstand the elevated temperature and humidity conditions encountered during use and storage yet still lose integrity upon contact with water in a toilet. Therefore, a water-disintegratable material having. mechanical integrity when dry is desirable.
Due to their water solubility, poly(vinyl alcohol) (hereinafter PVOH) and poly(ethylene oxide) (hereinafter PEO) have potential as component materials for water-disintegratable films, fibers, and flushable products. PEO,—(CH2CH2O)n—,is a commercially available water-soluble polymer that can be produced from the ring opening polymerization of the ethylene oxide, Because of its water-soluble properties, PEO is desirable for flushable applications. However, there is a dilemma in melt processing PEO. Low molecular weight PEO resins have desirable melt viscosities and melt pressure properties for melt processing but have limited solid state properties when melt processed into structural articles, such as films, and high molecular weight PEO has limited processability.
PVOH is also a commercially available water-soluble polymer. PVOH is made by hydrolyzing poly(vinyl acetate). PVOH resins have relatively high strength compared to PEO resins. Advantageously, PVOH resins are available that are both water-soluble and thermoplastic. However, these PVOH resins have low ductility and are inherently brittle. Therefore, there is a need to improve the ductility of water-soluble resins, namely PVOH, while still maintaining dry strength and water solubility.